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- Title
Nm23-H1 Protein Binds to APE1 at AP Sites and Stimulates AP Endonuclease Activity Following Ionizing Radiation of the Human Lung Cancer A549 Cells.
- Authors
Zhang, Zhi-Min; Yang, Xue-Qin; Wang, Dong; Wang, Ge; Yang, Zhen-Zhou; Qing, Yi; Yang, Zhi-Xiang; Li, Meng-Xia; Xiang, De-Bing
- Abstract
Non-metastatic protein-23 homolog-1 (Nm23-H1) is a multifunctional protein with DNase and histidine protein kinase activities. Human apurinic endonuclease-1 (APE1) is the AP endonuclease DNA base excision repair (BER) enzyme involved in several important cellular functions. Since the relationship between Nm23-H1 and APE1 proteins is unclear, we evaluated their interaction at different time points after irradiating human lung cancer A549 cells with X-rays. We found that Nm23-H1 and APE1 overexpression was induced by irradiation in a dose- and time-dependent manner. Subcellular distribution pattern of both proteins was reversed after irradiation. After irradiation, APE1 that initially showed nuclear localization was gradually increased in the cytoplasm, whereas Nm23-H1 that mainly showed cytoplasmic localization was gradually increased in the nuclei of A549 cells. Nm23-H1 and APE1 interaction was demonstrated by His-pull-down and co-immunoprecipitation assays. The presence of Nm23-H1/APE1 complex in X-ray-irradiated A549 cells was also detected by DNA affinity precipitation analysis of a DNA fragment containing an AP site. Although the AP endonuclease activity of Nm23-H1 was too weak to be detected, the AP endonuclease activity of APE1 was increased with the enhanced Nm23-H1 expression. In conclusion, our data point to a mechanism by which Nm23-H1 protects cells against oxidative stress through the engagement of DNA BER enzyme APE1.
- Subjects
IONIZING radiation; PROTEIN kinases; ENDONUCLEASES; DNA repair; OXIDATIVE stress; LUNG cancer
- Publication
Cell Biochemistry & Biophysics, 2011, Vol 61, Issue 3, p561
- ISSN
1085-9195
- Publication type
Article
- DOI
10.1007/s12013-011-9238-9